Method of coating ferrous bodies with other metals



Patented June 30, 1936.

PATENT OFFICE METHOD OF COATING FERROUS BODIES WITH OTHER METALS Anselmo Ortiz Rodriguez, Valverde-Leganes, Spain N 0 Drawing.

Application May 18, 1935, Serial No. 22,267. In Poland June 14, 1934 8 Claims.

In my copending application Serial No. 707,290, filed January 19, 1934, I have disclosed a process of eliminating the carbon from the surface of ferrous bodies which are to be coated with a nonferrous metal. In this process the ferrous bodies, prior to the application of the metal, are passed through an atmosphere of a decarburizing agent at a relatively high temperature. Ammonium chloride is designated as a particularly advantageous decarburizing agent.

The ammonium chloride vapor, notwithstandng its efficient decarburizing action on the ferrous bodies, is somewhat inconvenient to use, inasmuch as it necessitates the employment of a relatively high temperature during the decarburizing operation. In some cases this gives rise to attacks upon the metal and causes secondary chemical reactions which are difiicult to avoid and which impair somewhat the efiiciency of the process. In addition, in the process disclosed in my prior application, the ammonium chloride is introduced into the decarburizlng apparatus in a solid state which requires a careful hand operation and is, therefore, relatively expensive.

I have now discovered a process of decarburizing the surface of ferrous bodies by means of which better working conditions may be employed, for example, lower temperatures and greater speeds, without any of the aforementioned disadvantages.

My new process utilizes certain chemical compounds, such as oxyhalides, oxyhalogenhydrates, and oxysalts of certain metals, for example, zinc and cadmium, which have the property of oxidizing carbon at temperatures approaching, but below, red heat, (900 F.) in order to transform the carbon on the ferrous bodies to carbon monoxide or carbon dioxide without oxidizing the iron base. Examples of compounds of this general class are ZnCI2.ZnO and Cd(OH) 2.CdCl2.

In practicing my new process of decarburizing the surface of ferrous bodies, various mechanical arrangements may be employed for producing these chemical compounds in a treating zone maintained at the appropriate temperature through which the ferrous body to be decarburized is placed or passed. Alternatively the chemical compounds may be produced outside of this zone and introduced into the same by any suitable arrangement.

As illustrative of my invention, excellentresults may be obtained by employing aqueous solutions of zinc or cadmium halides, for example, 211012 and CdClz. If an iron wire, for example, is to be decarburized prior to being coated with metal, the wire may be wetted by an aqueous solu- The zinc oxychloride that is formed remains adherent on the ferrous body at first in a solid state and then'passes through a liquid state and finally to a vaporous state due to the temperature of the treating zone. In the vaporous state the zinc oxychloride oxidizes the carbon present on the surface of the ferrous body accordingto the following reaction:

It will be noted that during the treatment hydrochloric acid is formed. This reacts with any iron oxide on the surface of the ferrous body to form chlorides and water which are eliminated from the reaction zone in a vaporous state. The process, therefore, deoxidizes as well as decarburizes the surface.

Instead of zinc chloride, which is given only as an example, other halides, oxyhalides, oxysalts or mixtures thereof may be used, and all of these compounds will react in the same manner.

If a halide of cadmium is employed, for example, cadmium chloride, cadmium oxychlorhydrate Cd(OH)2.CdCl2 will be formed as the intermediate reaction product. The entire process can be combined into a single equation as follows:

- within the scope of my invention as defined in the following claims:

I claim:

1. In a method of coating ferrous bodies with non-ferrous metals, the step of decarburizing and deoxidizing the surface of said ferrous bodies prior to the coating, which comprises subjecting the ferrous bodies to an atmosphere of a compound selected from the group consisting of the oxyhaiides, oxyhalogenhydrates, and oxysalts of zinc and cadmium, said atmosphere being maintained at a temperature such that the carbon E non-ferrous metals, the step of decarburizing and deoxidizing the surface of said ferrous bodies prior to the coating, which comprises subjecting the ferrous bodies to an atmosphere of a material seiected from thegroup consisting of the halides, oxyhalides, oxyhalogenhydratesf oxysalts of zinc'and cadmium and mixtures thereof, said atmosphere being maintained at a temperature subh that the carbon present on 'the ferrous bodies is transformed into carbon oxides and other impurities on the surface of the ferrous bodies are eliminated in a gaseous state, without oxidizing the ferrous bodies. J

3. In a method of coating ferrousbodies with non-ferrous metals, the step of decarburizing and deoxidizing the surface of said ferrous bodies prior-to the coating, which comprises subjectin the ferrous bodies to an atmosphere of zinc oxychloride, said atmosphere being maintained at a temperature such that the carbon present on the ferrous bodies is transformed into carbon oxides and other impurities on the surface of the ferrous bodies are eliminated in a gaseous state, without oxidizing the ferrous bodies.

4. In a method of coating ferrous bodies with non-ferrous metals, the step of decarburizing and deoxidizing the surface of said ferrous bodies prior to the coating, which comprises subjecting a theferrous bodies to an atmosphere ofcadmium oxychlorhydrate. said atmosphere being maintained at a temperature such that the carbon present on the ferrous'bodies is transformed into carbon oxides and other impurities on-tiie surface of the ferrous bodies are eliminated in a gaseous state,- without oxidizing the ferrous bodies.

5. In a method of coating ferrous bodies with non-ferrous metals, the step of forming an atmosphere of a compound selected from the group consisting of oxyhalides, oxyhalogenhydrates, and

consisting of the halides of zi'ncand cadmium, and

subjecting the ferrous bodies t'osaid atmosphere which is maintained at a temperature such that 5' the carbon present on the ferrous bodies is transformed into carbon oxides and other impurities on the surface of the ferrous bodies are eliminated in a gaseous-state, without oxidizing the ferrous bodies. r 5 10 6. In a method of coating ferrous bodies with non-ferrous metals, the step of decarburizing and deoxidizing the surface. of said ferrous bodies prior to the coating, which comprises coating said ferrous bodies with an aqueous solution of a com- 15 pound selected from the'grou'p consisting of the halides of zinc and cadmium, and subjecting the bodies to a temperature at which the water and halide will react to res-m an oxysalt and at which. the carbon present oriithe ferrous bodies is trans- 20 formed into carbon oxides afid other impurlties on the surface of the ferrous bodies are eliminated in a gaseous state, without oxidizing the ferrous bodies. y l a 7. In a method of coating ferrous bodies with 25 non-ferrous rhetals, the step of decarburizing and deoxidizing the surface of said ferrous bodies prior to the coating, which comprises coating said ferrous bodies with an aqueous solution of mine chloride, and'subjectihg the bodies to a tem'pe'ra- 3 ture at which the water and halide will react to form zinc oxychloride, and at which the carbon present on the ferrous bodies is transformed into carbon oxides, and other impurltiesfon the surface *of the ferrous'bodies are eliminated in a gaseous state, without oxidizing the feifrous bodies.

8. In a method of coating ferrous bodies with non-ferrous metals, the step of decarburizing and deoxidizing the surface of said ferrous bodies prior'to the coating, which comprises coating said ferrous bodies with anaqueus solution of cadmium chloride, and subjecting the bodies to a temperature at which the water and'halide will react to form cadmium oxychlorhydrate, and at which the carbon present on the ferrous bodies 45 is transformed into earbon oxides and other impurities on the surface of the ferrous bodies are eliminated in a gaseous state, without oxidizing the ferrous bodies.

QANSELMO OR'I'IZ RODRIGUEZ. 

